Generally, a light emitting device using light emitting diodes is widely used in a variety of fields, such as a billboard, a traffic light, a bus direction board, or the like, and includes a printed circuit board formed in a certain plate shape, a plurality of diodes closely disposed in a entirety of a front surface of the printed circuit board and connecting to each other with a circuit and a control unit controlling to light the light emitting diodes to display various letters, figures or the like. However, because the light emitting means includes a plurality of light emitting diodes closely disposed in the printed circuit board, the light emitting means has large power consumption, and thus, a cost of manufacturing and maintaining the light emitting means increases. Also, because of high heat occurring in the diodes, a life of the light emitting diode is shortened, and thus, a malfunction occurs frequently. Moreover, the light emitting means displays letters or figures using a type of dot emitting when the light emitting diodes are being closely disposed in the printed circuit board, and thus, when the light emitting means is applied to a traffic light, light emitted from diodes directly irradiates and blinds a driver to cause a car accident. However, if the number of the diodes disposed in the traffic light decreases so at to prevent a driver from being blinded by the light, a cognitive power greatly decreases.
To remove the limitation, a related art light emitting device including a light guide plate, a LED module, a front plate, and a body casing is provided. The light guide plate is formed of a transparent material and a plate shape, and a plurality of irradiating lines formed in a horizontal and vertical direction are formed in a back side of the light guide plate. The LED module includes a printed circuit board formed in a long bar shape a length of which corresponds to a length of the side of the light guide plate, and a plurality of diodes disposed in other side of the printed circuit board at a certain interval. Here, the diodes are disposed to be adjacent to one side or both sides of the light guide plate, and light emitted from the LED moves along to the irradiating lines for the light guide plate to output plane light. The front plate is formed in a plate shape, is installed on the front side of the light guide plate, and outputs light transferred from the light guide plate. Also, various characters, photos, drawings, or the like are printed on the front plate. The light guide plate in which the LED module is installed, and the front plate are built in the body casing. The related art light emitting device outputs plane light through the light guide with a small number of LEDs to decrease power consumption, and enhances visibility of letters, photos, drawing or the like.
However, in the related art light emitting device, to install the LED module in a side surface of the light guide, a worker has to wrap the LED module together with the side surface of the light guide plate using an aluminum tape or an insulating tape to tightly contact the LED module and the light guide plate when the LED module formed in a thin and long bar shape is being tightly contacted the side surface of the light guide plate by hand of a worker. Therefore, an installing work is very difficult and needs many times. Also, when the LED module is attached to the light guide plate with the aluminum tape or the like, many cases where the side surface of the light guide plate does not exactly face the LED module, and is dislocated with the LED module occur, and thus, light-emitting efficiency decrease. Moreover, if the LED module formed in a long bar shape is used for a long time, the LED module is transformed by heat generated in the LED module to be dislocated to be separated from the side surface of the light guide plate. Therefore, light emitted from the LED in the LED module is not efficiently transferred to the light guide plate, and radiation of heat is not performed efficiently in the LED module, and thus, a plurality of LEDs are damaged in a short time.
Moreover, when the LED module is damaged or broken to be replaced or repaired, the LED module has to be separated by removing the aluminum tape after the light guide plate in which the LED module is installed, the front plate, or the like are taken out of the inside of the body casing, and then, a new LED module has to be installed. Therefore, it is difficult to replace and repair the LED module and many time are need.
In Korean Utility Model Registration No. 20-0396887 as a related art, an advertisement plate, which includes a frame having an open front side and formed in a shape where both sides of an upper portion and a lower portion are bent, a plurality of light emitting diodes disposed along a length direction of the frame, a block frame installed in the frame, and a plurality of advertising blocks slid and assembled to be inserted into the block frame, is disclosed. In the advertisement plate, both ends of the frame are covered with a stopper and a bolt is coupled when the block frames are being inserted into the frame in a row. Therefore, it is inconvenient and complicated to couple the advertisement plate with the stopper, the bolt, or the like. Also, there is not a light guide plate in which an irradiating line is cut. Moreover, a plurality of an advertisement block, in which an advertising copy is formed using a type of intaglio, configures one advertising letter. Therefore, to form a different advertising letter, an existing advertisement block has to be removed, and a new advertising letter has to be reinstalled with advertisement blocks in each of which a new advertising copy is formed using a type of intaglio. Therefore, an overall process of installing and assembling the advertisement plate is complicated and a cost of replacing the advertisement block greatly increases.